1. Field of the Invention
The present invention relates to an image processing apparatus, an imaging processing method, and a computer product for extracting digital watermark data from image information.
2. Description of the Related Art
In recent years, images accumulated or registered in an image processing apparatus are transferred to an external apparatus, such as a personal computer (PC), through communication and output to a printer from the external apparatus more often than ever. Accordingly, problems such as counterfeiting and use of the images in defiance of copyrights are concerns. To tackle such problems, information necessary to prevent the counterfeiting and to identify an author is embedded in an image. Digital watermarking is often used to embed such information in an image. Various technologies are currently proposed as the digital watermarking.
For example, Japanese Patent Application Laid-Open No. 2002-10057 discloses a color-image-forming apparatus that adds tracking data to a print image as digital watermark data. Specifically, the color-image-forming apparatus adds, to the digital watermark data, data for tracking a destination apparatus to which the image is output, to form a tracking pattern. Then, the color-image-forming apparatus combines the tracking pattern with print data, and then outputs the print data to a printer.
However, in the above color image forming apparatus, if the destination apparatus does not have a function of extracting the digital watermark data, the tracking data is failed to be extracted. In other words, the digital watermark embedded in image data with a predetermined embedding method can only be extracted with an extraction method conforming to the predetermined embedding method. Thus, the digital watermark cannot be extracted with an extraction method not conforming to the predetermined embedding method.